Secondary battery management device, secondary battery, and secondary battery management program

ABSTRACT

A secondary battery management device is connected with electronic equipment using a secondary battery as a driving power supply via the Internet. The secondary battery management device acquires performance information of the secondary battery from the electronic equipment, and measures a degradation level of performance of the secondary battery during a predetermined unit period. The secondary battery management device estimates a degrading speed of the secondary battery on the basis of the degradation level. 
     The secondary battery management device may notify a user of the electronic equipment of the replacement timing of the secondary battery, use fees of the secondary battery, and the like.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 16/913,031, filed on Jun. 26, 2020, which is acontinuation application of International Application No.PCT/JP2018/048010, filed on Dec. 27, 2018, which claims priority to andthe benefit of Japanese Patent Application No. 2017-250585, filed onDec. 27, 2017. The contents of these applications are incorporatedherein by reference in their entirety.

BACKGROUND OF INVENTION 1. Field

The present invention relates to management of secondary batteries and,in particular, to a technology for managing usage of secondarybatteries.

2. Description of Related Art

The market of secondary batteries has been steadily growing. Secondarybatteries have been used in a wide range of products such as electricvehicles, mobile terminals, power-assisted bicycles, and uninterruptiblepower supply systems. Secondary batteries are characteristic in beingusable for a long term by repeating charge and discharge. Secondarybatteries vary from small-size and low-cost ones to large-size andhigh-cost ones depending on intended uses thereof. Typically, a user whopurchased a secondary battery purchases another secondary battery at theend of the product life of the previous battery.

Patent Literature 1 describes a technology for predicting electricitydemand, and adjusting power supply at charging facilities on the basisof the prediction result. Although the technology of Patent Literature 1is aimed at vehicles, usage patterns of which are relatively easy topredict, it remains, however, unclear whether sufficient predictionaccuracy is achieved.

Related Art List

Patent Literature 1: JP 2017-112830 A

The present inventors have conceived an idea that lending ortransferring secondary batteries to a wide range of uses and accessingthe secondary batteries or electronic equipment using the secondarybatteries as necessary may enable provision of various information dataon usage of secondary batteries to users. Because secondary batterieshave been used in a large number of pieces of electronic equipment,collection of various measured values using the secondary batteries mayenable, in addition to prediction of demands, provision of informationuseful to uses and developments of secondary batteries.

SUMMARY OF INVENTION

The present invention has been achieved on the basis of recognition ofthe aforementioned problems, and a chief object thereof is to provide atechnology for providing users with information on usage of secondarybatteries.

A secondary battery management device according to an aspect of thepresent invention is connected with electronic equipment using asecondary battery as a driving power supply via a communication network.

The device includes: a performance information acquiring unit to acquireperformance information of the secondary battery from the electronicequipment; a degradation measuring unit to measure a degradation levelof performance of the secondary battery during a predetermined unitperiod; and a degradation estimating unit to estimate a degradationlevel of the secondary battery at a predetermined future time point onthe basis of the degradation level of the performance of the secondarybattery.

A secondary battery according to an aspect of the present invention isremovably mounted on electronic equipment as a driving power supply ofthe electronic equipment.

The secondary battery includes: a recording medium; and an equipment IDacquiring unit to acquire an equipment ID of the electronic equipment,and record the equipment ID in the recording medium.

The present invention facilitates provision of information on usage ofsecondary batteries to users.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a hardware configuration diagram of a secondary batterymanagement system.

FIG. 2 is a graph schematically illustrating an aging degradationpattern of a secondary battery.

FIG. 3 is a functional block diagram of a secondary battery managementdevice.

FIG. 4 is a data structure table of battery management information.

FIG. 5 is a flowchart illustrating processes for calculation of usefees.

FIG. 6 is a flowchart illustrating processes for ordering secondarybatteries.

FIG. 7 is a data structure table of degrading behavior historyinformation.

FIG. 8 is a graph schematically illustrating an aging degradationpattern of a secondary battery depending on use history.

FIG. 9 is a data structure table of behavior aggregate information.

FIG. 10 is a functional block diagram of a secondary battery accordingto a second embodiment.

FIG. 11 is a circuit diagram of a measurement circuit that measuresdischarge capacity of a secondary battery.

FIG. 12 is a graph illustrating degradation of SOH (capacity maintenancerate) as a secondary battery is used.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a system in which information on secondary batteries iscollected via a communication network will be described as a firstembodiment, and a system in which information is saved in secondarybatteries and collected at replacement or charging of the secondarybatteries will be described next as a second embodiment. The firstembodiment and the second embodiment will be collectively referred to as“the embodiments”, or will be referred to as “the present embodiment”when the embodiments are not particularly distinguished from each other.While information is collected at replacement in the description below,information may be collected at charging. In addition, while applicationto secondary batteries is described in the embodiments, a similar systemcan be built for fuel cells.

First Embodiment

FIG. 1 is a hardware configuration diagram of a secondary batterymanagement system 200.

In the secondary battery management system 200, a mobile terminal 202,an electric vehicle 204, an aircraft 206, a ship 208, and the like thatuse secondary batteries as driving power supplies are connected with asecondary battery management device 100 via the Internet 212.Hereinafter, devices and equipment that use the secondary batteries asdriving power supplies will collectively be referred to as “electronicequipment 210”. Each of the secondary batteries is leased from anoperator (hereinafter referred to as a “system operator”) of thesecondary battery management device 100. Users of the electronicequipment 210 need not purchase secondary batteries but leases thesecondary batteries from the system operator and regularly pay the feesfor use of the secondary batteries. In the present embodiment, the feefor use of a secondary battery is determined on the basis of thedegradation level of the secondary battery (details of the degradationlevel will be described later).

The secondary battery management device 100 is also connected with asecondary battery manufacturer 216 that manufactures secondarybatteries, and a financial institution 214 that settles payments of usefees. The secondary battery management device 100 periodically measuresthe degradation level each secondary battery. In the present embodiment,the degradation level is measured monthly. For example, when thesecondary battery of the electric vehicle 204 has a degradation level of5% on October 31, and a degradation level of 8% on November 30, the usefee of November is determined on the basis of a degradation level of 3%(=8−5). The secondary battery management device 100 notifies the user ofthe electric vehicle 204 of the use fee, and the user pays the use feethrough the financial institution 214.

When the degradation level of a secondary battery becomes apredetermined value or higher, the secondary battery management device100 notifies the user that the secondary battery is to be replaced. Inthis case, the secondary battery management device 100 instructs thesecondary battery manufacturer 216 to deliver a new secondary battery tothe user, and the secondary battery manufacturer 216 collects the usedsecondary battery. The secondary battery management device 100 can alsomanage the replacement timings of secondary batteries of the electronicequipment 210, and notify the secondary battery manufacturer 216 of aproduction forecast.

The secondary battery management device 100 also collects variousinformation data from users of secondary batteries. The secondarybattery management device 100 collects data indicating the usage ofsecondary batteries, and feeds back (provides information on) thecollected data to the developers of the secondary batteries and thedevelopers of the electronic equipment 210, details of which will bedescribed later. Through such provision of information, the systemoperator cooperates towards development of secondary batteries andelectronic equipment 210 using the secondary batteries.

In the description below, electronic equipment 210 is identified by an“equipment ID”, the user of the electronic equipment 210 is identifiedby a “user ID”, and a secondary battery is identified by a “battery ID”.

FIG. 2 is a graph schematically illustrating an aging degradationpattern of a secondary battery.

The horizontal axis represents time, and the vertical axis representsthe performance of the secondary battery. The secondary batteryperformance is expressed by internal resistance, discharge capacity,electromotive force (voltage), current during charge and discharge, andthe like as indices. Herein, the discharge capacity of a secondarybattery is presented as a typical example of the “performance”. Eachtime a secondary battery repeats charge and discharge, the dischargecapacity (output) gradually decreases.

Time point t0 corresponds to the timing of the beginning of use of asecondary battery subjected to measurement. The discharge capacity atthis point is an initial capacity. In the present embodiment, thedegradation level is defined as degradation level (%)=100×{(initialcapacity)-(measured capacity)}/(initial capacity). The measured capacityrefers to the discharge capacity of the secondary battery at ameasurement time point. At time point to, the initial capacity is equalto the measured capacity, and the degradation level is thus 0(%). Assumethat the secondary capacity is to be replaced when the degradation levelof the secondary battery is 20(%) or higher, or in other words, when themeasured capacity is 80(%) of the initial capacity. The degradationlevel at replacement, that is 20(%) in the example above, will bereferred to as “degradation threshold”.

Time point t1 is a time point a predetermined unit period after timepoint t0, such as one month after time point t0. At this point, themeasured capacity is 90(%) of the initial capacity, and the degradationlevel is 10(%). Because the secondary battery has degraded by 10(%)during a unit period T1 from time point t0 to time point t1, thesecondary battery management device 100 determines the use fee of thesecondary battery during the unit period T1 on the basis of 10(%) thatis the amount of change in the degradation level. In a case where theuse fee per degradation level of 1(%) is JPY 1,000, the use fee of thesecondary battery during the unit period T1 is JPY 10,000 (=1,000×10).

Time point t2 is a time point a unit period (one month) after time pointt1. The degradation level at time point t2 is assumed to be 15%. Becausethe secondary battery has degraded by 5(%) during a unit period T2 fromtime point t1 to time point t2, the secondary battery management device100 calculates the use fee of the second battery during the unit periodT2 to be JPY 5,000 (=1,000×5). In this manner, the secondary batterymanagement device 100 determines the use fee of the second battery onthe basis of the amount of change in the degradation level of thesecondary battery during each unit period.

In FIG. 2 , assume that time point t2 is the latest measurement timepoint. At time point t2, the secondary battery management device 100also estimates replacement time point t3 (future time point) of thesecondary battery. The secondary battery management device 100 mayestimate the replacement time point of the secondary battery to be atime point at which a line connecting the discharge capacity at timepoint t1 and the discharge capacity at time point t2 and the degradationthreshold intersect with each other.

FIG. 3 is a functional block diagram of the secondary battery managementdevice 100.

Respective components of the secondary battery management device 100 areimplemented by hardware including arithmetic units such as centralprocessing units (CPUs) and various coprocessors, storage devices suchas memories and storages, and wire or wireless communication linesconnecting the components, and software for supplying processinginstructions to the arithmetic units. Computer programs may beconstituted by device drivers, an Operating System, various applicationprograms on upper layers thereof, and libraries providing commonfunctions to the programs. Blocks described below do not representcomponents in hardware units but represent bocks in functional units.The same is applicable to a functional block diagram of a secondarybattery 300 in a second embodiment (see FIG. 10 ).

The secondary battery management device 100 includes a communicationunit 102, a data processing unit 104, and a data storage unit 106.

The communication unit 102 performs communication processing with theelectronic equipment 210 and the like via the Internet 212. The datastorage unit 106 stores various data. The data processing unit 104performs various processes on the basis of data acquired by thecommunication unit 102 and data stored in the data storage unit 106. Thedata processing unit 104 also functions as an interface between thecommunication unit 102 and the data storage unit 106.

The communication unit 102 includes a reception unit 108 that acquiresdata from external devices, and a transmission unit 110 that transmitsdata to external devices. The reception unit 108 includes a performanceinformation acquiring unit 112, a use history acquiring unit 114, anequipment ID acquiring unit 116, a user information acquiring unit 118,and a payment information acquiring unit 120.

The performance information acquiring unit 112 acquires performanceinformation from the electronic equipment 210. The performanceinformation refers to information indicating the performance of asecondary battery that is a driving power supply for the electronicequipment 210, such as nominal voltage, internal resistance, capacity,the number of charging times, charging rate, and the type of thesecondary battery. The use history acquiring unit 114 acquires usehistory from the electronic equipment 210. The use history isinformation indicating the manner in which the user has used theelectronic equipment 210. For example, in a case of a secondary batteryin the electric vehicle 204, information indicating driving history suchas sudden start and steep turn of the electric vehicle 204 may beacquired as the use history. In a case of a secondary battery in themobile terminal 202, information indicating an application executed bythe mobile terminal 202 may be acquired as the use history. The usehistory may also include information on various use states such ascharge timings, the amount of charge on a single charge, and thetemperature of the location of the electronic equipment 210.

The equipment ID acquiring unit 116 acquires the equipment ID of theelectronic equipment 210. The user information acquiring unit 118acquires user information from the electronic equipment 210. The userinformation refers to information representing the attributes of eachuser of the electronic equipment 210, such as the sex, the age, theplace of residence, and the occupation of the user. When a userregisters the user information on the electronic equipment 210, the userinformation acquiring unit 118 may collect the user information from theelectronic equipment 210. The payment information acquiring unit 120receives a payment completion notification from the financialinstitution 214.

In addition, the reception unit 108 may regularly acquire positioninformation indicating the location of the electronic equipment 210(secondary battery).

The transmission unit 110 includes a degradation estimation notifyingunit 122, a fee notifying unit 124, a replacement notifying unit 126,and an order notifying unit 128.

The degradation estimation notifying unit 122 notifies the electronicequipment 210 of degradation estimation. The degradation estimationrefers to estimation on when and how much a secondary battery being usedwill be degraded. The fee notifying unit 124 notifies the electronicequipment 210 of the use fee (an actual measured value and an estimatedvalue). The replacement notifying unit 126 notifies the user of theelectronic equipment 210 of whether or not the secondary battery needsreplacing or a future time point at which replacement will be needed.The order notifying unit 128 instructs the secondary batterymanufacturer 216 to produce and deliver a secondary battery.

The data processing unit 104 includes a degradation measuring unit 130,a fee calculating unit 132, a payment managing unit 134, an estimationunit 136, and a degrading behavior specifying unit 138.

As described with reference to FIG. 2 , the degradation measuring unit130 calculates the degradation level of a secondary battery. The feecalculating unit 132 calculates the use fee of a secondary battery. Thepayment managing unit 134 manages status of payments of use fees of eachuser on the basis of billing and payment completion notifications of theuse fees of a secondary battery. The degrading behavior specifying unit138 specifies usage that accelerates degradation of a secondary battery(hereinafter referred to as “degrading behavior”).

The estimation unit 136 performs various forecasting calculations on thebasis of the degradation level of a secondary battery. The estimationunit 136 includes a degradation estimating unit 140, a fee estimatingunit 142, and a replacement estimating unit 144.

As described with reference to FIG. 2 , the degradation estimating unit140 estimates how the degradation of a secondary battery will evolve onthe basis of degradation history of the secondary battery. The feeestimating unit 142 estimates future use fees of a secondary battery onthe basis of the degradation estimation of the secondary battery. Thereplacement estimating unit 144 estimates replacement timing of asecondary battery.

FIG. 4 is a data structure table of battery management information 150.

The battery management information 150 is stored in the data storageunit 106. When a secondary battery is set on the electronic equipment210, the electronic equipment 210 reads the battery ID set for thesecondary battery, and transmits the battery ID together with theequipment ID and the user ID to the secondary battery management device100. In addition, the electronic equipment 210 regularly transmits thedischarge capacity (measured capacity) of the secondary battery as theperformance information to the secondary battery management device 100.The degradation measuring unit 130 calculates the degradation level ofeach secondary battery, and registers the calculated degradation levelsin the battery management information 150. The fee calculating unit 132calculates the use fee of each secondary battery on the basis of theamount of change in the degradation level of the secondary batteryduring a unit period.

According to the battery management information 150 illustrated in FIG.4 , a secondary battery with a battery ID=B01 (hereinafter referred toas a “secondary battery (B01)”) is used as a driving power supply forelectronic equipment 210 (A01) of a user (P06). The current degradationlevel of the secondary battery (B01) is 2(%), and an unpaid use fee isJPY 200. The battery management information 150 provides information ona large number of secondary batteries regarding who use the secondarybatteries, for what types of electronic equipment 210 the secondarybatteries are used, how the secondary batteries are used, and how muchuse fees are charged in an integrated manner. The battery managementinformation 150 may also include other information such as userinformation registered therein.

Alternatively, a secondary battery itself, instead of the electronicequipment 210, may have communication functions. The secondary batterymay acquire the equipment ID, the user ID, the use history, the userinformation, and the like from the electronic equipment 210, andregularly transmit the performance information, the use history, theequipment ID, the battery ID, the user information, and the like to thesecondary battery management device 100. Note that, for privacyprotection, the user may be allowed to limit the information to betransmitted to the secondary battery management device 100 by theelectronic equipment 210 or the secondary battery.

FIG. 5 is a flowchart illustrating processes for calculation of usefees.

The processes illustrated in FIG. 5 are performed regularly at anyinterval such as once a week or once a day. The secondary batterymanagement device 100 of the present embodiment is assumed to performthe processes illustrated in FIG. 5 once a month for each user. In theexplanation of FIG. 5 , the processes are assumed to be performed for auser P1. The secondary battery management device 100 collects variousinformation data from the electronic equipment 210 (S10). Specifically,the performance information acquiring unit 112 acquires the performanceinformation of the secondary battery, the use history acquiring unit 114acquires the use history, the equipment ID acquiring unit 116 acquiresthe equipment ID, and the user information acquiring unit 118 acquiresthe user information of the user P1.

The degradation measuring unit 130 calculates the degradation level onthe basis of the performance information (discharge capacity) (S12). Thedegradation measuring unit 130 updates the battery managementinformation 150. Other information in the battery management information150 is also updated on the basis of the collected information. The feecalculating unit 132 calculates the use fee of the secondary battery onthe basis of the amount of change in the degradation level during onemonth (S14). The degradation measuring unit 130 performs variousforecasting calculations on the basis of the collected data (S16).Specifically, the degradation estimating unit 140 calculates thedegrading speed of the secondary battery, that is, in other words, whenand how much the secondary battery will be degraded on the basis thedegradation history obtained so far. The fee estimating unit 142estimates the use fee up to a future time point on the basis of thedegradation estimation. For example, in a case where the degradationlevel is estimated to increase by 3(%) during the next one month, thefee estimating unit 142 estimates the use fee for the next one month tobe JPY 3,000 (=1,000×3). The replacement estimating unit 144 estimatesthe replacement timing of the secondary battery.

The transmission unit 110 provides various notifications to the user P1(S18). The degradation estimation notifying unit 122 providesnotification of the degradation estimation made by the replacementestimating unit 144, the fee notifying unit 124 notifies the use fee(billed amount) and the estimated amount of the next use fee of thesecondary battery, and the replacement notifying unit 126 providesnotification of whether or not the secondary battery needs to bereplaced or estimated replacement timing.

The financial institution 214 withdraws the use fee from the account ofthe user P1, and transmits a payment completion notification to thesecondary battery management device 100. Similar processes are regularlyperformed for every user.

FIG. 6 is a flowchart illustrating processes for ordering secondarybatteries.

The secondary battery management device 100 performs the processesillustrated in FIG. 6 once a month. The secondary battery managementdevice 100 aggregates the replacement timings of a number of secondarybatteries. For example, the replacement estimating unit 144 aggregatesthe total number of secondary batteries that will need to be replacedduring a period from two months later to three months later (S20). Theorder notifying unit 128 orders the estimated number of secondarybatteries from the secondary battery manufacturer 216 (S22). Such acontrol method enables the secondary battery manufacturer 216 tominimize the secondary batteries in stock and grasp an appropriatequantity of secondary batteries to be produced.

FIG. 7 is a data structure table of degrading behavior historyinformation 160.

The degrading behavior history information 160 is stored in the datastorage unit 106. The degrading behavior history information 160 isprovided for each secondary battery. In the secondary battery managementdevice 100, a plurality of degrading behaviors F1 to F3 are defined inadvance. For example, the degrading behavior F1 may be sudden start ofthe electric vehicle 204, the degrading behavior F2 may be fastcharging, and the degrading behavior F3 may be use of a secondarybattery at a site at high temperature (25° C. or higher, for example).Herein, assume that the degrading behaviors are defined by the systemoperator.

In FIG. 7 , the numbers of times of the degrading behaviors F1 to F3 areextracted from the use history of the secondary battery (B01) used bythe user (P06). The degrading behavior specifying unit 138 updates thedegrading behavior history information 160 each time the use history isacquired in S10 of FIG. 5 . The secondary battery (B01) is used by theelectronic equipment 210 (A01) and the user (P06) (see FIG. 4 ).According to the degrading behavior history information 160 illustratedin FIG. 7 , in November 2017, the user (P06) did the degrading behaviorF1 four times, the degrading behavior F2 three times, and the degradingbehavior F3 0 times on the electronic equipment 210(A01) using thesecondary battery (B01) as a driving power supply.

Alert thresholds T1 to T3 are set in advance for the degrading behaviorsF1 to F3, respectively. Assume the alert threshold T1=5 times, the alertthreshold T2=10 times, and the alert threshold T3=2 times. When thenumber of times of a degrading behavior Fn per month has exceeded thealert threshold Tn, the degradation estimation notifying unit 122notifies the user of the degrading behavior Fn. For example, when thenumber of times of the degrading behavior F1 per month has reached thealert threshold T1=5 times, the degradation estimation notifying unit122 notifies the user of the possibility that the degrading behavior F1done a number of times degraded the secondary battery (hereinafterreferred to as a “degrading behavior notification”). In November 2017,because none of the number of times of the degrading behaviors exceededthe alert thresholds, no degrading behavior notification was provided.

In October 2017, the user (P06) did the degrading behavior Fl eighttimes. Because this exceeds the alert threshold T1=5 times, thedegradation estimation notifying unit 122 notifies the user (P06) of thedegrading behavior notification regarding the degrading behavior F1. Thedegrading behavior notification makes the user (P06) aware of thetendency of doing the degrading behavior F1. The user (P06) may haverecognized that fast charging or the like is a degrading behavior, butis often unaware of what degrading behavior the user (P06) actuallytends to do. The degrading behavior notification enables the user to beaware of what behavior would minimize degradation of the secondarybattery, or in other words, what degrading behavior the user tends todo. Appropriate degrading behavior notification can be provided on thebasis of the use history of the user, which helps the user understandhow their behavior can be changed to extend the life of the secondarybattery.

FIG. 8 is a graph schematically illustrating an aging degradationpattern of a secondary battery depending on use history.

The progress of degradation of a secondary battery varies depending onthe usage thereof. In one example, the degradation estimating unit 140may classify users into a plurality of types depending on the frequencyof degrading behaviors. For example, assume that users with the averagenumber of times of the degrading behavior F1 described with reference toFIG. 7 per month being smaller than five times are classified as a typeX1, users with the average number thereof being equal to or larger thanfive times and smaller than 15 times are classified as a type X2, andusers with the average number thereof being equal to or larger than 15times are classified as a type X3. A user of the type X3 is consideredas being more likely to degrade the secondary battery than a user of thetype X1. In the data storage unit 106, aging degradation patterns ofsecondary batteries associated with the types X1 to X3 are defined inadvance.

Next, assume a case where degradation of a new secondary battery (B10)is estimated. Assume that the user (P55) of the secondary battery (B10)is of the type X3 according to the past use history of the user (P55).In this case, the degradation estimating unit 140 estimates thedegrading speed, the use fee, the replacement timing, and the like ofthe secondary battery (B10) on the basis of the aging degradationpattern defined in association with the type X3. According to FIG. 8 ,the user (P55) is estimated to face the need to replace the secondarybattery (B10) at time point t4 (one and a half months later, forexample), which is relatively close to the time point t0 that is thebeginning of use. Such a control method enables estimation of a futuredegrading speed of a secondary battery in view of the use history of theuser of the secondary battery. In addition, when data indicating thatmany of users belonging to the type X3 have actually used the secondarybattery longer than the time point t4 (one and a half months later) areobtained, the degradation estimating unit 140 may modify the agingdegradation pattern (model) associated with the type X3.

The degradation may be estimated on the basis of use history other thandegrading behaviors. The degrading speed of a secondary battery may varydepending on the sex, the place of residence (whether it is a warm areaor a cold area), and the age of the user. For example, in a case wherestatistical data indicating that users living in Nagano Prefecture aresignificantly likely to degrade a secondary battery than users living inGifu Prefecture are obtained, the degradation estimating unit 140 mayprovide different aging degradation patterns for users in NaganoPrefecture and users in Gifu Prefecture.

The degradation may be estimated on the basis of information other thanuse history. The degrading speed of a secondary battery can beconsidered as varying depending on the types of electronic equipment210. The degradation estimating unit 140 may set a plurality of agingdegradation patterns depending on the types of electronic equipment 210,and estimate the degrading speed of a secondary battery on the basis ofthe aging degradation pattern of the electronic equipment 210 subjectedto measurement. For example, different aging degradation patterns may beapplied to use of a secondary battery in a sports car and use thereof ina minivan.

The aging degradation patterns are also considered as varying dependingon the types of secondary batteries. For example, the aging degradationpattern of a lithium-ion secondary battery is considered as beingdifferent from that of a sodium-sulfur battery.

FIG. 9 is a data structure table of behavior aggregate information 170.

The behavior aggregate information 170 is stored in the data storageunit 106. The behavior aggregate information 170 is used to identifydegrading behaviors from use histories collected in regard to aplurality of secondary batteries and a plurality of users. While thedegrading behaviors are defined and set by the system operator in FIG. 7, a method for finding out degrading behaviors from use histories (bigdata) of a large number of users is explained in FIG. 9 .

The degrading behavior specifying unit 138 extracts use histories whenthe degradation level per day exceeds 5(%) from large quantities ofaggregated use history data. Behaviors G1 to G4 illustrated in FIG. 9are behaviors representing usage of the electronic equipment 210. Assumethat there is an event 1 in which a behavior G4 done by a certain useronly once per day degraded the performance of a secondary battery by5(%) or higher in a day. In this case, the behavior G4 is estimated tobe likely to significantly degrade the secondary battery by being doneonly once. The degrading behavior specifying unit 138 sets the degradingability of 1 to the behavior G4. The “degrading ability” used herein isan index indicating how much a behavior (usage of a secondary battery)degrades a secondary battery.

In addition, assume that there is an event 2 in which a behavior G2 doneby a certain user 20 times per day degraded the performance of asecondary battery by 5(%) or higher in a day. In this case, the behaviorG2 is estimated to be likely to degrade the secondary battery by beingdone 20 times. The degrading behavior specifying unit 138 sets thedegrading ability of 1/20 to the behavior G2.

Assume that there is an event 3 in which the behavior G1 done by acertain user eight times per day and the behavior G2 done by the userfour times per day degraded the performance of a secondary battery by5(%) or higher in a day. Because the degradation due to the behavior G2is ( 1/20)×4=⅕, ⅕ of the degradation of 5(%) is attributed to thebehavior G2. The degrading behavior specifying unit 138 calculates thedegrading ability of the behavior G1 to be 1/10 (=(1−⅕)×(⅛)).

Assume that there is an event 4 in which the behavior G1 done by acertain user eight times per day and the behavior G3 done by the usersix times per day degraded the performance of a secondary battery by5(%) or higher in a day. Because the degradation due to the behavior G1is ( 1/10)×8=⅘, ⅘ of the degradation of 5(%) is attributed to thebehavior G1. The degrading behavior specifying unit 138 calculates thedegrading ability of the behavior G3 to be 1/30 (=(1−⅘)×(⅙)).

As described above, the degrading ability of the behavior G1 is 1/10,the degrading ability of the behavior G2 is 1/20, the degrading abilityof the behavior G3 is 1/30, and the degrading ability of the behavior G4is 1. The degrading behavior specifying unit 138 specifies behaviorswith degrading abilities of a predetermined value or larger, such as1/15 or larger, as “degrading behaviors”. In the case of the exampleabove, the degrading behavior specifying unit 138 specifies thebehaviors G1 and G4 as degrading behaviors on the basis of the usehistories. Collection of degradation histories and use histories inregard to a large number of secondary batteries enables the degradingbehavior specifying unit 138 to reasonably detect what usage is likelyto degrade a secondary battery and how much the usage is likely todegrade the secondary battery.

Second Embodiment

In the description of the first embodiment, electronic equipment 210 orsecondary batteries have the communication functions, and the secondarybattery management device 100 regularly accesses the electronicequipment 210, etc. to collect various data on the secondary batteries.In the second embodiment, various data on secondary batteries havingstorage functions are collected at replacement of the secondarybatteries, instead of data collection via a communication network.

FIG. 10 is a functional block diagram of a secondary battery 300according to the second embodiment. The secondary battery 300 includesbattery cells 302, a charge/discharge control unit 304, a dataacquisition unit 306, and a data storage unit 308. The battery cells 302are an electricity storage. The charge/discharge control unit 304controls charge and discharge of the battery cells 302. The batterycells 302 and the charge/discharge control unit 304 are functionalblocks included in known secondary batteries.

The data acquisition unit 306 acquires various data from the electronicequipment 210. The data storage unit 308 (recording medium) isconstituted by a nonvolatile memory. The data acquisition unit 306includes an equipment ID acquiring unit 310, a use history acquiringunit 312, and a user information acquiring unit 314. The equipment IDacquiring unit 310 acquires the equipment ID of the electronic equipment210 in which the secondary battery 300 is installed. The use historyacquiring unit 312 acquires the use history from the electronicequipment 210. The user information acquiring unit 314 acquires the userinformation from the electronic equipment 210. In the second embodiment,assume that the electronic equipment 210 associated with the secondarybattery 300 includes an interface for providing various information datasuch as the equipment ID to the secondary battery 300.

In the second embodiment, the user replaces the secondary battery 300 attheir own discretion. The system operator reads various information datasuch as the performance information by reading the data storage unit 308of the collected secondary battery 300. The system operator calculatesthe degradation level and the use fee based on the degradation level inthe same manners as in the first embodiment, and the user pays the usefee to the system operator. The use fee may be paid in one lump sum, butpayment in installments reduces the burden of the cost for introductionand replacement of the secondary battery 300 on the user in a mannersimilar to the first embodiment.

Note that the secondary battery 300 of the second embodiment may havethe functions of the degradation measuring unit 130, the fee calculatingunit 132, the estimation unit 136, the degrading behavior specifyingunit 138, and the like of the secondary battery management device 100.In this case, a user can check various information data such as thedegradation level and the use fee as necessary even when usingelectronic equipment 210 that cannot be connected to the Internet 212.

The secondary battery management system 200 and the secondary battery300 have been described above with reference to the first and secondembodiments.

In the secondary battery management system 200, the user of a secondarybattery need not purchase a secondary battery, which reduces the initialcost in introduction of the secondary battery (electronic equipment210). The secondary battery management device 100 charges a use fee of asecondary battery on the basis of the degradation level the secondarybattery instead of the amount of use thereof such as a discharge amountor the number of charging times. The use fee for a user who uses asecondary battery carefully becomes low, which encourages users to havean incentive to use secondary batteries carefully even though they areleased. Making users aware of such usage that extends the lives ofsecondary batteries is also effective in reducing environmental load.

In a system in which the use fee is determined on the basis ofmeasurement of the number of charging times or the like of a secondarybattery by a sensor in the secondary battery or electronic equipment210, the risk of sensor failure and data falsification can hardly beavoided. Measurement of the number of charging times is also problematicin determination on how much charging rate is to be counted as onecharging. In a case of a secondary battery of an electric vehicle, amethod calculating the use fee on the basis of the traveling distancecan be considered, but similar risk remains. In contrast, degradation ofa secondary battery is a physical phenomenon, and thus enables provisionof reliable information on how much the secondary battery has been used.The degradation level, which is a physical phenomenon, cannot befalsified. Even if the performance information (discharge capacity)transmitted from electronic equipment 210 to the secondary batterymanagement device 100 while a secondary battery is being used isincorrect, the reliable degradation level can be obtained at replacementof the secondary battery, and the use fee to be finally paid will thusbe a proper value. A higher fee can be charged to a user who carelesslyuses a secondary battery. This eliminates the need for leasers ofsecondary batteries to excessively guard against the risk associatedwith leasing.

A secondary battery is a “device for storing electricity”. It is notreasonable to determine the use fee of a secondary battery on the basisof the discharge amount or the number of charging times of the secondarybattery. This is because the costs for electricity for chargingsecondary batteries are imposed on users. In contrast, in the presentembodiment, the use fee is a price (compensation) for impairmentassociated with the degradation level of a leased secondary battery,that is, impairment caused by the use of such device as a secondarybattery. The basis for the use fee is therefore reasonable. Becausesecondary batteries are devices (rented devices) whose degradationlevels can be easily measured, they are suitable for building such aunique business system.

The secondary battery management device 100 is capable of notifying auser of the degrading speed, future use fees, replacement timing, andthe like of a leased secondary battery. In addition, indication of whatdegrading behavior a user tends to do among multiple degrading behaviorscontributes to improvement of the user's behavior.

The secondary battery management device 100 is also capable of analyzingwhat usage is likely to degrade secondary batteries by collecting usehistories in regard to a large number of secondary batteries. Forexample, in a case where data indicating that secondary batteries arelikely to be degraded by traveling on snowy roads are obtained, it canbe determined that it is more rational to use gasoline engine as a powersource of a hybrid car on a snowy road instead of the secondary battery.In a case where data indicating that secondary batteries of a certaintype are likely to be degraded by charging using solar power areobtained, new charging/discharging circuits for reducing the loads onbattery cells may be necessary. In a case where data indicating thatsecondary batteries mounted on electric vehicles of an automobilemanufacturer M1 are less prone to degradation and that secondarybatteries mounted on electric vehicles of an automobile manufacturer M2are prone to degradation, it is advantageous for the automobilemanufacturer M1 in that the data can be used in making proactive appealto customers. In addition, the automobile manufacturer M2 recognizes thenecessity for designs enabling efficient use of secondary batteries,which is considered as contributing to promotion of peripheraltechnologies relating to secondary batteries.

The secondary battery management system 200 is also advantageous inpreventing data relating to secondary batteries from being kept only bymanufacturers of electronic equipment 210. Because data on secondarybatteries (general-purpose products) used in multiple electronicequipment 210 and on the electronic equipment 210 can be collected onthe basis of the secondary batteries, a wealth of findings on secondarybatteries and electronic equipment 210 are expected to be provided. Forexample, collection of geographical information on where secondarybatteries have been used facilitates reasonable determination onefficient arrangement of charging stations for secondary batteries.

In the second embodiment, data such as use histories are accumulated inthe secondary battery 300. In addition, the use fee depending on thedegradation level is charged at replacement of the secondary battery300. This enables a system similar to the secondary battery managementsystem 200 of the first embodiment to be built even in a developingcountry with insufficient communication environment or a secluded placethat is hard of access.

The present invention is not limited to the embodiments described aboveand modifications thereof, and any component thereof can be modified andembodied without departing from the scope of the invention. Componentsdescribed in the embodiment and modifications can be combined asappropriate to form various other embodiments. Some components may beomitted from the components presented in the embodiments andmodifications.

Modifications

In the description of the embodiments, various information data such asthe performance information, the use history, the equipment ID, and theuser information are collected for each secondary battery. A large-sizedsecondary battery is often constituted by an assembly of cells (smallsecondary batteries). In a modification, the battery ID may be assignedto each of cells instead of a secondary battery (an assembly of cells),and the performance information and the like on each cell may becollected.

For example, assume a secondary battery including 25 cells arranged in asquare of 5×5. Assume that outer cells of the secondary battery turn outto be more prone to degradation than inner cells as a result ofcollection of various information data on the secondary battery. Whensuch data are obtained, design of a charge control circuit for reducingloads on the outer cells is considered as being effective in extendingthe product life of the secondary battery. Alternatively, design of astructure of a secondary battery that facilitates replacement of outercells relative to inner cells may be effective. In this manner,collection of information on each cell may also enable a wealth offindings on the design of secondary batteries to be provided.

In the embodiments, the degree to which the discharge capacity islowered is defined as a degradation level. The degradation level canalso be defined with data other than discharge capacity. The internalresistance of a secondary battery is known to increase each time thesecondary battery repeats charge and discharge. The secondary batterymanagement device 100 may define the degradation level (%) as {(measuredresistance)−(initial resistance)}/(initial resistance). Alternatively,the degradation level may be defined on the basis of both a degradationlevel A calculated on the basis of the discharge capacity and adegradation level B calculated on the basis of the internal voltage, asan average of the degradation level A and the degradation level B, forexample. Alternatively, the degradation level may be defined on thebasis of the degree to which the battery capacity is lowered with time,or the degree to which the mileage on a full charge of an electricvehicle 204 is lowered. Alternatively, the degradation level may bedefined on the basis of an open-circuit voltage (OCV), an open-endvoltage, or the like instead of the discharge capacity.

The secondary battery management device 100 may hold aging degradationpatterns (models) of secondary batteries, and estimate degradation onthe basis of the aging degradation patterns. Such models may be formedas neural network models. The use histories and the like of secondarybatteries that are degraded relatively rapidly may be analyzed, variousparameters such as behaviors, the types of electronic equipment 210, anduse environment (such as temperature) may be set in input layers, andhow much these parameters affect the degradation of the secondarybatteries may be analyzed. The degradation of each secondary battery maythen be estimated on the basis of the neural network models. Degradingbehaviors may be specified on the basis of weighting factors set forrespective models of input layers (parameters). Accumulation of data onsecondary batteries elaborates the models.

In the description of the embodiments, the replacement notifying unit126 provides notification of the replacement timing of a secondarybattery. The secondary battery management device 100 may include acharging position notifying unit for providing notification of thepositions of charging stations for secondary batteries. The secondarybattery management device 100 may also include a charging timingnotifying unit for notifying the electronic equipment 210 of the timingfor charging. The use history acquiring unit 114 of the secondarybattery management device 100 may further regularly acquire chargingrate information on each secondary battery. The charging timingnotifying unit may transmit a notification for prompting a user tocharge the secondary battery to electronic equipment 210 using thesecondary battery when the charging rate of the secondary battery is apredetermined threshold, such as 30%, or lower.

In the description of the first embodiment, information on secondarybatteries is regularly collected. Alternatively, information may becollected when secondary batteries are charged. For example, because anelectric vehicle 204 needs to be stopped for charging of the secondarybattery, information on the secondary battery is readily collected fromthe electric vehicle 204 during charging.

In the description of the second embodiment, information is collected atreplacement of secondary batteries. In the second embodiment as well,information may be collected at charging of secondary batteries. Forexample, when charging stations have communication functions, thecharging stations may read various information data from the datastorage unit 308 of the secondary battery 300 and transmit theinformation to the secondary battery management device 100.

Secondary batteries that have exceeded a degradation threshold may besubjected to secondary use. For example, secondary batteries withdegradation levels exceeding 20% (hereinafter referred to as “degradedsecondary battery”) may be reused by an operator of an energy storagesystem (ESS). For example, assume that the degradation level ofsecondary battery used by a user A has exceeded the degradationthreshold. In this case, the replacement notifying unit 126 of thesecondary battery management device 100 notifies the user A that thedegraded secondary battery is to be replaced, and notifies a user B whooperates an ESS that a degraded secondary battery has come out. Thesecondary battery management device 100 may include a matching unit thatmatches the user A with the user B. The matching unit intermediatesbetween the user A and the user B to form a consensus on the price andthe time for picking up the degraded secondary battery. After theconsensus is formed, the system operator of the secondary batterymanagement device 100 sends the degraded secondary battery collectedfrom the user A to the user B.

In addition, when the degradation level of the degraded secondarybattery has exceeded a predetermined threshold, such as 50%, thedegraded secondary battery may be broken down to be recycled. Thereplacement notifying unit 126 may notify the user B that the degradedsecondary battery is to be recycled when the degradation level of thedegraded secondary battery used by the user B has exceeded 50%.

The cost for introducing a secondary battery does not have to be zero.For example, half the price of a secondary battery may be initiallycharged and the remaining amount may be included in use fees.

In the embodiments, the method for finding out behaviors that degradesecondary batteries from use histories has been explained.Alternatively, behaviors for avoiding degradation of secondary batteriesmay be extracted. For example, when a user P2 who degrades the secondarybattery little even though the user P2 frequently charges the secondarybattery, the behaviors of the user P2 may be investigated. After suchinvestigation, the know-how of the user P2 for extending the life of asecondary battery may be presented to other users.

It is also possible to estimate electric power generation on the basisof the degradation levels of a large number of secondary batteries. Forexample, a secondary battery with a high degradation level has a smallpower storage. Thus, when the number of relatively degraded secondarybatteries is large, the necessary amount of power generation is expectedto be small. In contrast, when the number of new or replaced secondarybatteries, or in other words, relatively less degraded secondarybatteries is large, the necessary amount of power generation is expectedto be large. The secondary battery management device 100 may estimatenot only the use fees but also necessary power amounts on the basis ofthe degradation levels of secondary batteries, and notify a powerproducer of the estimation.

In the embodiments, degradation of secondary batteries has beendescribed. The present invention is, however, also applicable tobatteries, other than secondary batteries, that are degraded. Forexample, outputs of fuel cells also lower as the fuel cells are used.Thus, the degradation levels of fuel cells may also be measured, andcollection of various information data thereon such as use histories,calculation of use fees, and the like may be performed. A “secondarybattery” used herein includes a “fuel cell” in a broad sense.

FIG. 11 is a circuit diagram of a measurement circuit 330 that measuresdischarge capacity of a secondary battery 300.

The secondary battery 300 includes a battery component 320 and aresistor component 322. When charge and discharge are repeated, a layeris gradually formed on an anode surface by reaction between graphiteused as an anode material of the secondary battery 300 and anelectrolyte. The resistor component 322 (internal resistance r) iscaused by the layer on the anode. When the internal resistance r=0, theelectromotive force E of the battery component 320 and the voltage Vapplied to an external resistor 324 are equal to each other. When theinternal resistance r is not zero, however, V=E−I·r, where I representsdischarge current, is satisfied, and the discharge voltage is lowered bythe resistor component 322. Thus, the degradation level of the secondarybattery 300 can thus be expressed by measuring the difference betweenthe OCV (open-end voltage) and discharge voltage as an index.

Typically, the degradation level of the secondary battery 300 isexpressed by States Of Health (SOH) as an index. The SOH represents acapacity maintenance rate, but may also be defined as the resistanceincrease rate of the internal resistance r. In the description below,the SOH is assumed to be the capacity maintenance rate. The SOH isdetermined by a discharge capacity value; the SOH is, however, alsoaffected by the current value and the temperature during measurement,and is thus evaluated in view of these values. Note that the capacity ofthe secondary battery 300 refers to the electric (charge) quantity thatcan be taken out from the secondary battery 300 in a fully charged statewhen the secondary battery 300 is discharged until the terminal voltageof the external resistor 324 reaches a predetermined cut-off voltage.

FIG. 12 is a graph illustrating degradation of the SOH (capacitymaintenance rate) as the secondary battery 300 is used.

The present inventors conducted experiments on the degrading speed ofthe secondary battery 300 associated with charge and discharge thereof.In the experiments, a cylindrical cell of a lithium-ion secondarybattery (secondary battery 300) having a size of 18 mm×65 mm was used.The initial capacity of the secondary battery 300 was 2,750 (mAh). Thetemperature during measurement was 25 degrees Celsius. Charge anddischarge of the secondary battery 300 were repeated, and the decrease(degradation) in the SOH with accumulated discharge capacity (mAh) wasmeasured.

Charge was deemed to be completed when the voltage reached 4.2 (V), anddischarge was deemed to be completed when the voltage reached 2.5 (V).The SOH was periodically measured while charge and discharge wererepeated.

A degradation curve P1 represents the tendency of the decrease in theSOH under a condition 1 based on safe driving of the electric vehicle204. A degradation curve P2 represents the tendency of the decrease inthe SOH under a condition 2 based on driving with quick acceleration ofthe electric vehicle 204. Under the condition 1, the capacity rate(C-rate) of charging was 0.2, the C-rate of discharging was also 0.2.The C-rate of charging or discharging the secondary battery 300 of 2,750(mAh) in one hour was defined as 1.0. The C-rate of 0.2 means thatcharging is relatively slow. Under the condition 2, the C-rate ofcharging was 0.2, and the C-rate of discharging was 0.8. Under thecondition 2, the discharge current was made larger than that in thecondition 1 to rapidly discharge the secondary battery 300. Note thatthe charge currents and the discharge currents of the degradation curveP1 and the degradation curve P2 were constant currents.

The experiments show that the secondary battery 300 is degraded fasterwhen the secondary battery 300 is rapidly discharged (degradation curveP2: condition 2) than when the secondary battery 300 is not rapidlydischarged (degradation curve P1: condition 1).

A user A1 is assumed to drive the electric vehicle 204 safely. In thecase of safe driving, the secondary battery 300 is estimated to bedegraded by about 2(%) when the accumulated discharge capacity reachesabout 360,000 (mAh). In contrast, a user A2 is assumed to performdriving with quick acceleration of the electric vehicle 204. In the caseof driving with quick acceleration operation, the secondary battery 300is estimated to be degraded by about 2(%) when the accumulated dischargecapacity reaches about 170,000 (mAh). Even though the user A1 uses moreelectrical energy than the user A2, the user A1 uses the secondarybattery 300 more carefully than the user A2, and is thus charged as muchuse fees as the user A2. Such a system provides an inventive for usersto use secondary batteries 300 carefully.

Manufacture of secondary batteries 300 involves a significant cost. Ifmany users can be led to use secondary batteries 300 with care, theresources and labor for manufacture of secondary batteries 300 in theworld as a whole can be effectively reduced.

In the first embodiment, special application software for measuringvoltage, current, and temperature (hereinafter referred to as“performance measurement software”) may be introduced to electronicequipment 210 such as the electric vehicle 204. In the secondembodiment, performance measurement software may be introduced to thesecondary battery 300. The performance measurement software regularlymeasures performance information such as the discharge capacity, andnotifies the secondary battery management device 100 of the performanceinformation. The performance measurement software only needs to havemeasurement functions and communication functions. The secondary batterymanagement device 100 calculates the degradation level on the basis ofthe performance information acquired from the performance measurementsoftware, and calculates the use fee of the secondary battery 300. Theperformance measurement software may calculate the degradation level onthe basis of the performance information and notify the secondarybattery manufacturer 216 of the degradation level.

Even if a malicious user falsifies or invalidates the performancemeasurement software, the user has to replace the secondary battery 300at some time point. Because the degradation level of the secondarybattery 300 can be measured at the replacement point, adjustment ofpayment at the replacement cannot be avoided even if the degradationlevel has been fudged during use of the secondary battery 300. In thecase of the electric vehicle 204, charging stations may acquire theperformance information of the secondary battery 300 when the secondarybattery 300 is charted at the charging stations. The charging stationsmay then transmit the performance information to the secondary batterymanagement device 100. Alternatively, measurers may regularly acquirethe performance information of individual secondary batteries 300.

The secondary battery management device 100 of the embodiments collectsperformance information from a large number of secondary batteries 300.For example, in a case where 50 million secondary batteries 300 of atype T1 have been distributed, such estimation as four million of thembeing expected to be replaced next month makes production schedulingeasier for the secondary battery manufacturer 216. Estimation ofreplacement timings of a large quantity of secondary batteries 300 in anintegrated manner by the secondary battery management device 100facilitates prevention of a dead stock of secondary batteries 300 due tooverproduction or loss of business opportunities due to underproduction.

As described above, the estimation of degradation of the secondarybattery 300 may be based on an aging degradation table. For example,assume a case where actual performance information as follows isobtained: when the secondary battery 300 is degraded by 5(%) in onemonth from replacement, the probability that the degradation level ofthe secondary battery 300 will reach 20(%) in two months fromreplacement is 3(%), the probability that the degradation level of thesecondary battery 300 reaches 20(%) in three month from replacement is15(%) . . . . In this case, an aging degradation table may be set on thebasis of the actual performance information. When such an agingdegradation table based on actual performance information is provided,future evolution of the degradation of a secondary battery 300 can beestimated by referring to the actual degrading speed and the agingdegradation table of the secondary battery 300.

In the first embodiment, special application software for measuringusage of electronic equipment 210 (hereinafter referred to as “usagemeasurement software”) may be introduced to the electronic equipment210. In the second embodiment, usage measurement software may beintroduced to the secondary battery 300. The usage measurement softwareacquires usage information of the electronic equipment 210, and notifiesthe secondary battery management device 100 of the usage information.For example, assume that the secondary battery 300 is mounted on mobileequipment such as the electric vehicle 204. In this case, the usagemeasurement software acquires the number of sudden starts, the number ofsudden stops, the average speed, and the highest speed per unit time ofthe mobile equipment, the percentage of time during which the mobileequipment traveled at speeds higher than a threshold in the travelingtime thereof, and the like as usage information. The usage measurementsoftware may also notify the secondary battery management device 100 ofa so-called eco-driving score (known technology) as usage information.The secondary battery management device 100 may estimate the degradationlevel of the secondary battery 300 on the basis of results innotification from the usage measurement software. For example, aplurality of aging degradation tables depending on eco-driving scoresmay be provided in advance. Upon receiving a score from an electricvehicle 204 to be measure, the degradation estimating unit may estimatefuture evolution of the degradation of the secondary battery 300 on thebasis of an associated aging degradation table.

A plurality of aging degradation tables may be provided depending on thetypes of secondary batteries 300. Alternatively, a plurality of agingdegradation tables may be provided depending on the types of electronicequipment 210 on which secondary batteries 300 are mounted. A pluralityof aging degradation tables may be provided depending on the attributesof users. The degradation estimating unit 140 may estimate thedegradation of a secondary battery 300 on the basis of the type of theuser, the type of electronic equipment 210, and the type of secondarybattery 300.

The degradation measuring unit 130 may calculate the degradation levelon the basis of a plurality of kinds of performance information. Forexample, the degradation measuring unit 130 may calculate thedegradation level on the basis of each of the amount of change in theinternal resistance and the amount of change in the capacity maintenancerate. The degradation measuring unit 130 may determine the highest, thelowest, the average or the median of a plurality of kinds of degradationlevels as a final degradation level of the secondary battery 300.Comprehensive determination of the degradation level of a secondarybattery 300 from degradation levels obtained from a plurality of aspectsin this manner enables more reasonable calculation of the degradationlevel.

Permissible values of the degradation level of a secondary battery 300(degradation thresholds) are considered as varying depending on users ofthe secondary battery 300. For example, a user A4 is assumed to use asecondary battery 300 with a degradation level of 90 to 100(%), andreplaces the secondary battery 300 when the degradation level becomeslower than 90(%). A user A5 is assumed to use a secondary battery 300with a degradation level of 70 to 100(%). In this case, the secondarybattery 300 with a degradation level lower than 90(%) that can no longerbe used by the user A4 is usable for the user A5. The aforementionedmatching unit may notify the user A5 that the secondary battery 300 ofthe user A4 is available at the replacement timing of the secondarybattery 300 of the user A4 or at a timing when the replacement thereofis expected. Alternatively, the matching unit may deliver the secondarybattery 300 that is no longer used by the user A4 to the user A5. Whenthe user A4 replaces the secondary battery 300, the matching unit maysearch for a user who can use this secondary battery 300, and inform theuser that the secondary battery 300 is available.

When no user who can use the secondary battery 300 that is no longerused by the user A4 is present, the replacement notifying unit 126 maydeliver the secondary battery 300 to a recycler.

The use fees of a secondary battery 300 may be determined on the basisof a purchase price of the secondary battery 300 and a degradationthreshold set as a measure of replacement. For example, assume that apurchase price of a secondary battery 300 is JPY 100,000, and that thesecondary battery 300 is to be replaced when the degradation levelreaches a degradation threshold of 20(%). In this case, because adegradation level of 20(%) is assumed to amount to a value of JPY100,000, the use fee per a degradation level of 1(%) may be JPY 5,000(=100,000+20). In this manner, the fee calculating unit 132 maycalculate a use fee associated with a degradation level on the basis ofthe purchase price of a secondary battery 300 and a degradationthreshold set by the user or the manufacturer of the secondary battery300. Such a control method enables reasonable calculation of use fees ofvarious types of secondary batteries 300 in the secondary batterymanagement system 200, which encourages users to participate in thelease system provided by the secondary battery management system 200 atease.

In addition, the secondary battery management device 100 can calculateuse fees of a variety of secondary batteries 300 in a simple and fairmanner on the basis of the purchase prices (selling prices) anddegradation thresholds, and is thus applicable to management of varioustypes of secondary batteries 300. Use fees of secondary batteries 300with high purchase prices are high, and use fees of secondary batteries300 that are less prone to degradation are low.

In the description of the embodiments, users of secondary batteries 300are charged use fees depending on the degradation levels. In some cases,a government can impose a tax on users of secondary batteries 300depending on the degradation levels. This encourages the public to makea conscious effort to use secondary batteries 300 carefully for a longertime, which contributes to effective use of precious resources. Inaddition, users who drive safely get preferential treatment in terms offees as compared with users who perform driving with quick acceleration,which can be expected to produce an effect of improving drivers'compliance with safety rules in driving electric vehicles 204.

Payments of use fees (costs) in small amounts based on the degradationlevels of secondary batteries 300 correspond to depreciation of purchaseprices of fixed assets in financial statements. The secondary batterymanagement system 200 may also make it easier for companies to introducesecondary batteries 300 in terms of accounting.

The following invention can be derived from the embodiments andmodifications.

A1. A secondary battery management device connected with electronicequipment via a communication network, the electronic equipment using asecondary battery as a driving power supply, the secondary batterymanagement device comprising:

a performance information acquiring unit to acquire performanceinformation of the secondary battery from the electronic equipment;

a degradation measuring unit to measure a degradation level ofperformance of the secondary battery during a predetermined unit period;and

a fee calculating unit to calculate a use fee of the secondary batteryfor the unit period depending on the degradation level.

A2. The secondary battery management device according to A1, furthercomprising:

a degradation estimating unit to estimate a degradation level of thesecondary battery at a predetermined future time point on the basis ofthe degradation level of the performance per unit period of thesecondary battery.

A3. The secondary battery management device according to A2, furthercomprising:

a fee estimating unit to estimate a use fee of the secondary battery fora predetermined unit period on the basis of the estimation of thedegradation level of the secondary battery; and

a fee notifying unit to notify a user of the electronic equipment of theestimated use fee.

A4. The secondary battery management device according to A2 or A3,further comprising:

a replacement estimating unit to estimate replacement timing of thesecondary battery on the basis of the estimation of the degradationlevel of the secondary battery; and

a replacement notifying unit to notify a user of the electronicequipment of the estimated replacement timing.

A5. The secondary battery management device according to any one of A1to A4, further comprising:

a use history acquiring unit to acquire use history of the electronicequipment from the electronic equipment; and

a degrading behavior specifying unit to refer to degradation history ofthe secondary battery and the use history, and specify a degradingbehavior performed by a user of the electronic equipment from among aplurality of degrading behaviors defined as usage that degrades thesecondary battery.

A6. The secondary battery management device according to A1, wherein

the performance information acquiring unit acquires, as the performanceinformation, a discharge capacity of the secondary battery, and

the degradation measuring unit measures, as the degradation level, adecrease in the discharge capacity during the unit period.

A7. The secondary battery management device according to any one of A1to A6, wherein

the fee calculating unit calculates the use fee depending on a type ofthe secondary battery on the basis of both a purchase price and adegradation threshold of the secondary battery.

A8. A secondary battery management program causing a computer toimplement:

a function of acquiring performance information of a secondary batteryfrom electronic equipment using the secondary battery as a driving powersupply;

a function of measuring a degradation level of performance of thesecondary battery during a predetermined unit period; and

a function of calculating a use fee of the secondary battery for theunit period depending on the degradation level.

What is claimed is:
 1. A secondary battery removably mounted onelectronic equipment as a driving power supply of the electronicequipment, the secondary battery comprising: a data storage unit; and adata acquisition unit to acquire data from the electronic equipment andsave the acquired data in the data storage unit.
 2. The secondarybattery according to claim 1, wherein the data acquisition unit includesan equipment ID acquisition unit that acquires, as the data, anequipment ID of the electronic equipment, and saves the acquiredequipment ID in the data storage unit.
 3. The secondary batteryaccording to claim 1, wherein the data acquisition unit includes a usehistory acquiring unit that acquires, as the data, use history of theelectronic equipment, and saves the use history in the data storageunit.
 4. The secondary battery according to claim 1, wherein the dataacquisition unit includes a user information acquiring unit thatacquires, as the data, user information of a user that uses theelectronic equipment, and saves the acquired user information in thedata storage unit.
 5. The secondary battery according to claim 1,further comprising: a charge/discharge control unit to control batterycharge and discharge on the basis of the acquired data.
 6. The secondarybattery according to claim 5, wherein the secondary battery includesbattery cells, and the charge/discharge control unit controls charge anddischarge of the battery cells.
 7. The secondary battery according toclaim 1, wherein the data storage unit is configured to allow anexternal device to read the saved data.
 8. The secondary batteryaccording to claim 1, further comprising: a degradation measuring unitto calculate a degradation level of the secondary battery on the basisof the saved acquired data.
 9. The secondary battery according to claim1, further comprising: a fee calculating unit to calculate a use fee ofthe secondary battery on the basis of the saved acquired data.
 10. Thesecondary battery according to claim 3, further comprising: anestimation unit to estimate one or more of how degradation of thesecondary battery will progress, a future use fee, and replacementtiming on the basis of the saved acquired use history.